The overall objective of the proposed investigations is to elucidate the molecular mechanisms which regulate the synthesis of phospholipids and triacylflycerols in eukaryotic cells. The approach is enzymological and focuses on in vitro studies of microsomal enzymes of glycerolipid synthesis. The purification of the rat liver microsomal diacylglycerol acyltransferase will be underteken. Detailed studies on the topography of glycerolipid biosynthetic enzymes in the transverse plane of microsomal vesicles will be undertaken. Studies on glycerolipid biosynthetic enzymes in 3T3-L1 preadipocytes will focus on short-term regulation by hormones, and changes in polypeptides in microsomes.